939003715 - N020 HORNS NOT WORKING

0PRELIMINARY CHECKSALL OKPROBLEMS ENCOUNTEREDACTION
Check, by operating the horn control on the steering wheel, that the travel is correctMove on to Step 1Travel not correctRemove the steering wheel and check that there are no impediments to the travel.Op. 4110A11 STEERING WHEEL - R+R FOR REPLACEMENT OR CHECK FOR VERSIONS WITH AIR BAGIf there are problems, replace the faulty component
1CHECK ON INTERVENTION OF FUSEALL OKPROBLEMS ENCOUNTEREDACTION
Check that the horn protective fuse has not blown.It can be found in the engine compartment junction unit and is the third fuse in the first row F10 (15 A).Move on to Step 2The fuse has blownReplace the fuse and search for the cause of the problem.
2RELAY CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Swap the horn relay feed T3 (it is the middle one in the top row) with the one for the main beam headlamps T2 (it is the first on the left in the top row) and check that the horn is working properly.Move on to Step 3The horn continues not to workRestore the relays to their places and move on to Step 4
3RELAY CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check that the main beam headlamps are working. If the result is positive, remove the horn relay feed and check that the contacts do not show signs of oxidation or deformation.End of diagnosis1. The main beam headlamps are not working1. Replace the main beam headlamp relay (which was originally the one for the horns)
2. There are problems with the contacts in the engine compartment junction unit.2. Renew the contacts.If necessary, replace the engine compartment junction unit    Op. 5505A13 ADDITIONAL JUNCTION UNIT IN ENGINE COMPARTMENT - R.R.
4RELAY ELECTRICAL CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Undo the fastenings for the engine compartment junction unit and check, using a tester, that the power supply and the earth for the horn relay feed are correct.    Op. 5505A13 ADDITIONAL JUNCTION UNIT IN ENGINE COMPARTMENT - R.R. Move on to Step 5Relay line electrical problems.Move on to Step 8
5HORN ELECTRICAL CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Using a tester, connect to the horn power supply line and check that whilst the horn is working the supply voltage is more than 11.4 V.Also check the continuity and the insulation of the lineMove on to Step 61. The voltage is below 11.4 V1. Check the cause of the power supply and restore the correct power supply.Possibly    See Test 5530BC BATTERY CHARGE CHECK
2. Other electrical problems2. Restore the correct electrical connections    See E3010 HORNS
6HORN POSITIONING CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check that both the horn casing and the bracket are not touching or are not in the immediate vicinity (less than 10 mm) of other objects (other components, cables, pipes, etc.)Move on to Step 7Horn bracket or casing interfering with other components.Eliminate the cause of the interference
7STEERING COLUMN SWITCH UNIT CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Remove the steering wheel and check that there is nothing preventing the operation of the horn control switch.Using a tester in parallel to the switch check that, whilst it is working, the supply voltage is more than 11.4 VMove on to Step 91. Switch stuck open1. Replace the steering wheelOp. 4110A11
2. Switch power supply problems.2. Replace the steering column switch unit.Op. 5550A12
8HORN CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Remove the horn and connect it directly to a battery charger.    Op. 5550B30 L/H OR R/H HORN (ONE) - R+R Check that a sound is produced and there are no unpleasant noises (knocking/buzzing)Move on to Step 9Sound faulty or no sound produced.Replace the horn    Op. 5550B30 L/H OR R/H HORN (ONE) - R+R
9ELECTRICAL CIRCUIT CHECKALL OKPROBLEMS ENCOUNTEREDACTION
The problem is due to the presence of an irregular electrical absorption source in the electrical system.Search for and eliminate this causeEnd of diagnosis